Vacuum pan



i ZZAU? J. HAMILL vAcUUM PAN March 2, 1943i.

Original Filed May 17, 1939 2 Sheets-Sheet l Marsh 2, 1943. HAMILL 2,312,407

Original Filed May 1'7, 1959 2 Sheets-Sheet 2 Patented Mar. 2, 1943 VACUUM PAN James Hamill, West Orange, N. J.

Original application. May 17, 1939, Serial N0. 274,253. Divided and this application June 18, 1941-, Serial N0. 398,657

tube sheets 5 and 6, respectively. Steam is ad-` mitted to the oalandria through an inlet 1 and condensate from the steam collects in a drain gutter 8 from which it may be conducted by one or more pipes 9.

As is customary, the bottom of the pan is provided with an inlet pipe I0 through which sugar syrup.to be concentrated is admitted and it is also provided with an outlet II through which tion of the ascending and descending currents in the circulating mass above the Calandria by inducing the ascending stream containing the vapors to rise to the surface of the mass in the pan without interfering with the descending stream which has been freed of its steam so that a. greater temperature differential will exist between the ascending and descending streams and the circulation of the mass thereby accelerated. i A primary feature of the invention consists in providing a vacuum pan having a calandria .with a tubular 'device which isy disposed above the downtake of the Calandria and which is provided with a plurality of sets of vertically spaced curved louvres each of which has an upwardly and outwardly inclined outer surface for deflecting the circulating mass ascending adjacent the tubular member away from the circulating mass descending therein.

Another feature of the invention consists in providing the tubular member with a plurality of sets of vertically spaced curved louvres, the louvres of one set being in staggered relation with respect to the louvres of another set and each of the louvres being inclined upwardly and outwardly.

Other and more specific features of the invention, residing in advantageous forms, combinations and relations of parts, will hereinafter appear and be pointed out in the claims.

In the drawings, Figure 1 illustrates 'a vacuum pan embodying my invention.

, would be liberated, much of it takes the shortestr the concentrated mass is discharged from the pan. The upper portion of the pan tapers inwardly to provide a dome l2 above which is located in the portion of the pan designated I3 a vapor separator (not shown). Leading from the vapor separator is the usual vapor outlet I4.

In the normal-operation of vacuum pans'of this type the initial charge of syrup admitted to the pan is of sufficient volume to cover the upper tube sheet 5, the level usually attained by the initial charge being approximately indicated by the dot and dash line I5. With the steam in the calandria 2 and a vacuum existing in the interior of the pan by virtue of the condensation of the vapors removed through the outlet I4, the normal circulation of the boiling mass in the pan is upwards in the tubes 4 and downwards in the downtake 3. As concentration of the mass proceeds, additional syrup is drawn into the vacuum pan at properly timed intervals through the inlet pipe ID, of which there may be a plurality, to promote the formation of crystals in the usual manner ,until the contents of the pan reach the strike level indicated approximately by the dot and dash line I6.

In the standard construction of vacuum pans where no attempt is made to separate the ascending and descending currents in the circulating mass above the Calandria, the ascending mass containing vapor bubbles converges toward the center of the pan and instead of rising to the surface of the mass where the entrained bubbles path of return to the under side of the Calandria by passing down the intake 4before rising to the surface. This interferes with and retards the descent of circulating currents returning from the surface. To eliminate this undesirable result, a tubular device l1 is provided above the downtake of the Calandria. 'I'his device defines a passageway for the descending circulating mass and it is so formed as to cause substantially all of the ascending circulating currents to rise to the surface of the mass where the entrained vapor bubbles are liberated. By compelling the ascending mass to rise to the surface before returning to the calandria, a greater temperature differential than is otherwise possible will exist between the ascending and descending currents and the circulation of the mass will, therefore, be accelerated. More rapid circulation also results from the circumstance that the diterence in density between the ascending and descending currents is increased by reason of the descending currents having been substantially freedof all vapor bubbles.

The tubular device II for separating the ascending and descending currents of the circulating mass consists of a plurality of sets of curved vertically spaced louvres or vanes, the sets of louvres being respectively designated by the reference numerals I8, I9, 20 and 2|, respectively. Interposed between the adjoining ends of the louvres of adjacent sets are vertically extending radially arranged plate-like members 22 by which the louvres are supported. The ends of the louvres abut against the supporting members and may be conveniently welded thereto, while the lower end of each of the supporting members may be advantageously anged as indicated at 23 for attachment, as by welding, to the upper tube' sheet 5 of the calandria.

The louvres of each set are so arranged that' .sheet so that ample opportunity is afforded for the circulation of the initial charge of syrup.

The outer surfaces of the louvres are inclined upwardly and outwardly so as to deflect the circulating mass ascending from the tubes 4 away from the column of circulating mass descending within the passageway which the louvres define. The inclination of the louvres is such, considering the vertical distance between the louvres, that the vapor bubbles in the ascending stream will be diverted outwardly suiiiciently to be intercepted by the next louvre above should the bubbles expand inwardly towards the descending mass. It has been found that best results are obtained if the louvres are preferably vertically spaced so that the angle designated A betweenthe horizontal and a line connecting the lower edge of one louvre with the upper edge of the subjacent louvre is no greater than approximately 50. This angle may, of course, be less than the amount indicated but to be certain that all entrained vapor bubbles will be caused to ascend to the surface of the circulating mass, it should not exceed 50% by any substantial amount.

The louvres of at least one set are arranged in staggered relation with respect to the louvres of one or more of the other sets so that the tubular device is provided with one or more peripheral openings at substantially every level which may be assumed by the mass within the pan. While the louvres I8 and I9 are shown in the drawings as being disposed at the same elevations and in staggered relation with respect to louvres and 2|, it will, of course, be appreciated that the louvres may be disposed in other staggered relationships and that a greater or `fewer number of sets of louvres may be employed.

From the foregoing, it will be perceived that simple and eiiective means have been devised for 'guiding the circulation o! the mass so as to compel the ascending circulating mass containing l vapor bubbles to rise to the surface and thus prevent it from interfering with the descending mass which has been freed of its vapor. Various modifications and changes in the specific structure illustrated andldescribed may, of course, be made without departing from the spirit of the invention as defined in the appended claims.

What I claim is:

l. The improvement in vacuum pans of the type having a Calandria provided with a downtake and a plurality of tubes, said improvement consisting of a tubular-like member positioned above the jdowntake in substantially vertical alinement therewith for promoting the circulation of the mass being concentrated in the pan, said tubular-like member providing a vertically extending passageway for the circulating mass descending toward the downtake and comprising a plurality of sets of vertically spaced arcuateV louvres, each of said louvres having an outer surface inclined upwardly and outwardly for deiiecting the circulating mass ascending adjacent the tubular member away from the column of circulating mass descending in said passageway and said tubular member having a plurality of overflow openings the upper and lower edges of which are respectively defined by the lower and type having a Calandria provided with a downtake and a plurality of. tubes, said improvement consisting of a tubular-like member positioned above the downtake in substantially vertical alinement therewith for promoting the circulation of the mass being concentrated in the pan, said tubular-like member lproviding a vertically extending passageway for'the circulating mass descending toward the downtake and comprising a plurality of sets of vertically spaced arcuate louvres, the louvres of one set being arranged in staggered relation with respect to the louvres of another set and each of said louvres being inclined upwardly and outwardly for deflecting the circulating mass ascending adjacent the tubular member away from the column of circulating mass descending in said passageway, the upper edges of the louvres of each `set being in substantial vertical alignment and said louvres providing the tubular-like member with a plurality of openings the upper and lower edges of which are respectively dened by the lower and upper edges of lsaid louvres.

3. The improvement in vacuum pans oi the type having a Calandria provided with a downtake and a plurality of tubes, said improvement consisting of a tubular-like member positioned above the downtake in substantially vertical 'alinement therewith for promoting the circulation of the mass being concentrated in the pan, said tubular-like member providing a vertically extending passageway for the circulating mass descending toward the downtakel and comprising a plurality of sets of vertically spaced arcuate louvres, and upright radially disposed plate-like supporting members for the louvres respectively interposed between and arranged in abutting relation with the adjoining end's of adjacent sets of louvres. each of said louvres having an outer surface inclined upwardly and outwardly to deflect the circulating mass ascending adjacent the tubular member away from the column of circulating mass descending in said passageway.

4. The improvement in vacuum pans of the type having a calandria provided with a downtake and a plurality of tubes, said improvement consisting of a tubular-like memberpositioned above the downtake in substantially Vertical alinement therewith for promoting the circulation of the mass being concentrated in the pan, said tubular-like member providing a vertically extending passageway for the circulating mass descending toward the downtake and comprising a plurality1 of sets of superimposed arcuate louvres, the lower edge of each louvre except the lowermost one of each setbeing spaced vertically above the upper edge of the next subjacent louvre to provide the tubular-like member with a plurality of openings, each of said louvres being inclined upwardly and outwardly to deect the circulating mass ascending adjacent the tubular member away from the column of circulating mass descending in said passageway and the upper edges of the louvres of each set being in substantial vertical alignment.

5. The improvement in vacuum pans of the type having a calandria provided with a downtake and a plurality of tubes, said improvement consisting of a tubular-like member positioned above the downtake in substantially vertical alinement therewith for promoting the circulation of the mass being concentrated in the pan, said tubular-like member providing a vertically extending passageway `for the circulating mass descending toward the downtake and comprising a plurality of sets of vertically spaced arcuate louvres, upright supporting members for the louvres respectively interposed between and arranged in abutting relation with the adjoining ends of adjacent sets of louvres, the louvres of one set being arranged in staggered relation with the louvres of another set and each of said louvres having an outer surface inclined upwardly and outwardly to deflect the circulating mass ascending adjacent the tubular member away from the column of circulating mass descending in said passageway.

Y JAMES HAMILL. 

